Sacroiliac Joint Fusion Methodology - Minimally Invasive Compared to Screw-Type Surgeries: A Systematic Review and Meta-Analysis

Background: Sacroiliac (SI) joint fusion represents a unique area of orthopedic surgery with procedural literature dating to the early 1920s, showing limited innovation in either technique or hardware over the last 90 years. Recent improvements in the diagnosis and treatment of SI joint dysfunction warrant comparisons to older surgical techniques. Objective: To evaluate treatment efficacies and patient outcomes associated with minimally invasive joint fusion in comparison to screw-type surgeries. Study Design: Systematic review and meta-analysis. Setting: Electronic databases, EMBASE, Pubmed (Medline), manual bibliography cross-referencing for published works until Dec. 31, 2017. Methods: A thorough literature search was performed in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Data repositories accessed included Pubmed and EMBASE, until Dec. 31, 2017. All studies evaluating sacroiliac joint fusion and reporting quantifiable outcome data were included. Exclusion criteria included nonhuman studies, qualitative reviews, and meta-analyses. Data compilation, coding, and extraction were performed using MedAware Systems proprietary software. Data from each study were extracted by 2 analysts, using software that allowed automatic comparisons of all data fields. The standardized mean difference (SMD) was used as a summary statistic for pooling outcomes data across studies. Multiple outcome measures were grouped into 3 categories, according to similarity of measurements - Pain, Disability/Physical Function, and Global/QOL. Results: A total of 20 studies had adequate data to calculate a SMD, and were included in the meta-analysis. Results of iFuse trials were compared to screw type trials, pooled in 3 categories of outcomes - Pain, Disability/Physical Function, and Global/QOL. The Pain category showed a statistically significant (P = 0.03) difference in outcomes for patients receiving the iFuse implant compared to screw types (SMD = 2.04 [95%CI: 1.76 to 2.33] vs. 1.28 [95%CI: 0.47 to 2.09]), with iFuse showing significantly better outcomes. The Disability category also showed a statistically significant (P = 0.01) difference in outcomes for patients receiving the iFuse implant compared to screw types (SMD = 1.68 [95%CI: 1.43 to 1.94] vs. 0.26 [95%CI: -1.90 to 2.41]), with iFuse showing significantly better outcomes. For Global/Quality of Life (QOL) outcomes, there was a significant difference (P = 0.04) between iFuse and screw-type procedures (SMD = 0.99 [95%CI: 0.75 to 1.24] vs. 0.60 [95%CI: 0.33 to 0.88]), with iFuse showing significantly better outcomes. There was a statistically significant correlation between lower baseline Oswestry Disability Index (ODI) and Short Form 36 Health Survey (SF-36) values and better post treatment outcomes (r2 = 0.47, P < 0.01, and r2 = 0.30, P < 0.01, respectively). An association was found between pain at baseline and better outcomes (r2 = 0.21, P < 0.01), where worse baseline pain was associated with better outcomes. Limitations: There was a limited number of studies in this meta-analysis with treatments that could be properly classified as screw-type. Conclusion: In this analysis, compared to screw-type surgeries, the iFuse system showed statistically superior outcomes. This was the case when outcome measures were classified into 3 main categories - Pain, Disability/Physical Function, and Global/QOL. Key words: Meta-analysis, systematic review, sacroiliac joint, sacroiliac joint fusion